Rotor-shaft connection



Feb. 2, 1960 w. DOBLE 2 ROTOR-SHAFT CONNECTION Filed Sept. 3, 1957 av HIS A TTOBNEYS HARE/6, (may, os'rse c Haze/s United States Patent YO ROTOR-SHAFT CONNECTION Warren Doble, North Hollywood, Calif., assignor to Jabsco Pump Company, Burbank, Calif., a corporation of California Application September 3, 1957, Serial No. 681,797

3 Claims. (31. 287-52) The present invention relates to means for transmitting rotation between a shaft and a rotor telescoped over the shaft, a primary object of the invention being to provide a torque-transmitting rotor-shaft connection which effectively prevents relative movement between the rotor and the shaft during rotation thereof so as to minimize wear, but which at the same time provides for a loose fit between the rotor and the shaft so that the rotor may be installed and removed readily without the use of any special tools or equipment.

, The invention is of particular utility as applied to a pump having an elastomeric impeller provided with flexible radial vanes, and is for the purpose of transmitting rotation of the shaft of the pump to a rotor having the form of an insert molded into and bonded to the elastorneric impeller. The impeller of a pump of this type mustbe replaced periodically and it is desirable,

and frequently essential, that such replacement be capamay be removed and installed manually.

In order to prevent excessive wear of the shaft and/ or the impeller insert due to the loose fit therebetween, the invention provides means foreffectively locking the impeller insert and the shaft together during rotation of the shaft, such means operating in response to a slight initial-rotation of the shaft relative to the impeller insert, which is an important feature of the invention;

An important object of the invention is to provide a torque-transmitting connection between the impeller insert and the shaft which produces engagement between the insert and the shaft at three circumferentially spaced points in response to a slight initial rotation of the shaft relative to the insert upon starting of the pump. This provides a stable three-point contact between the insert and the shaft and insures that there is always a force component available to oppose the side load resulting from the flexure of the vanes of the impeller and result ing from the pumping load.

Another object of the invention is to provide a torquetransmitting connection between the impeller insert and the pump shaft which centers the impeller on the shaft in response to a slight initial rotation of the shaft relative to the impeller.

The foregoing results are achieved in accordance with the present invention by providing the shaft with two substantially diametrically opposite, longitudinally extending, flat-forming chordal walls and by providing the impeller insert with an internal key which is engageable with one of the flats at a point spaced from the circumferential center thereof, the longitudinal edges of the other of the walls being brought into engagement with the interior of the impeller insert upon a slight initial Patented Feb. 2, 1960 be apparent to those skilled in this art in the light of the present disclosure, may be attained with the exemplary embodiment of the invention described in detail hereinafter and illustrated in the accompanying drawing, in which:

Fig. 1 is a longitudinal sectional view of a pump which embodies the invention;

Fig. 2 is a transverse sectional view of the pump which is taken as indicated by the arrowed line 2-2 of Fig. 1; and

Fig; 3 is a fragmentary transverse sectional view duplicating a portion of Fig. 2 and illustrating the operation of the invention.

Referring to the drawing, the numeral 10 designates a pump havinga housing 12 which is provided with an impeller bore 14 and which is provided with inlet and outlet ports 16'and 18 in communication with the impeller bore. .Disposed within the impeller bore 14 at one side thereof and between the inlet and outlet ports 16 and 18 is a cam 20, the cam being shown as secured to the housing 12 by a screw 22. The inner surface of the cam cooperates with the peripheral wall of the impeller bore 14 to provide an impeller chamber designated generally by the numeral 24, the inner surface of the cam providing the impeller chamber with a minimum radius between the inlet and outlet ports.

Extending longitudinally intothe impeller chamber 24 and coaxial with the impeller bore 14 is a shaft 26, shown as the shaft of an electric motor 28 the housing of'which is connected to the pump housing 12 by a structure 30. The shaft 26'has telescoped thereover a generally cylindrical impeller insert 32, there being a torque-transmitting connection 34 between the shaft 26 and the insert 32 which will be described hereinafter. Molded onto and bonded to the impeller insert 32 is an elastomeric impeller 36 having flexible radial vanes 38 whichalternately engage the peripheral wall of the inipeller bore 14 and the inner surface of the cam'20jas the-impeller 36 is rotated within the impeller chamber 24 bythe shaft 26. V t q, 7 As will be apparent, th'e cam .20 flexesthe-yanesjinwardly in the vicinity of the outlet port 18 to decrease the volumes of the intervane spaces adjacent the outlet port, thereby discharging fluid from the intervane spaces into the outlet port. As the vanes 38 disengage the cam 20, which occurs in the vicinity of the inlet port 16, the intervane spaces are increased in volume to draw fluid to be pumped into the intervane spaces from the inlet port. This is the characteristic pumping action of a pump of this type, as is well known in the art.

Considering the torque-transmitting connection 34 of the invention, the shaft 26 is provided with two substantially diametrically opposite, longitudinally extending, nonconvex, chordal walls which form at least substantially parallel flats 40.. The impeller insert 32 is provided with an internal key 42 which is engageable with one of the flats 40, at a point spaced circumferentially from the center thereof. In the construction illustrated, the impeller insert is merely a sheet metal tube onto which the impeller 36 is molded and bonded, the key 42 being an inwardly struck dimple.

The diameter of shaft 26 and the inside diameter of the impeller insert 32 are so related that there is suflicient clearance between the shaft and the insert to permit installation of the impeller 36 on and removal thereof from the shaft readily, preferably manually without the I t .t 1 2,923,563

use of any" tools. This-greatly facilitates replacement of j36. This slight relative rotation bet-Ween the-shaft 26 "and the impeller insert- 32 results in engagement of I the key42 with one of the flats 40'a't -a point circnmferentiaily spaced from the center thereof and results in engagement "of the longitudinal edges of the other fl-at 40 i with the pe-t ripheral wal1=of the opening through the insert," which centers the impeller on the shaft. While engagement 43etween "the interior of the insert82 and the longitudinal edges of one of the flats 40 is referredto herein, in actual practicenarrow longitudinalbands of the-shaft 26, each 'bordered on one=side "by one of it-he=longitudinal edges of such fiat, engage the insert. 7 i

The-foregoing intererigagenient between the shaft 26 and "the impellerinsert 32,' af ter -a slight initial rotation of the shaft relative to the insert, produces stable threepoint contact or engagement between the'shaft and the "insert, as indicated -by-=the arrows'44. 'Such three-point 'contac-t insures'that there isalways a force component acting-in-=a direotionto -resist the side load imposed on theimpe'llerby thecam 20 and by the pumping load.

- With the foregoing construction, once the shaft :26

'has rotated relative to the impeller insert 32 sufiiciently-to and substitutions may be embodiment disclosed without departing from the spirit jproduce the three-poin'tengagement indicated by the arrows 44 no further relative movement of the-shaftand the insert takes place. In otherwords, even with a side load on the -impeller*36 which varies in directionrelative *to the key 42 asthe impeller rotates, .the impeller" insert 32 will not work back and forthon the shaft '26 as the shaft and the impeller continue to rotate-due to'thefact :t-hat the three-pointcontact-describedinsures the constant c Although an exemplary embodiment of the invention 0 has been disclosed herein for purposes of illustration, it

will be understood that various changes, modifications incorporated in the specific of the invention as defined :by the following claims:

1. In combination: a shaft having two substantially diametrically opposite, longitudinally extending, nonconveX wallseach having two longitudinal edges and a longitudinal centerline midway between its said longitudinal edges; and a member telescoped over said shaft and having thereon an internal key engaging one of said walls between-said longitudinal centerline of, said one wall and one of said longitudinaledges of said one wall upon relative rotation of said shaft and said member, said, shaft engagingthe interior of said member adjacent said longitudinal edges of the other of said walls upon said relative rotation ,of saidshaft andnsaid member.

2. Incombination: a shaft, having two substantially diametrically opposite, longitudinally extending flats each having two longitudinal edgesanda longitudinal centerline midway between its said longitudinal edges; and a "member telescoped over :said shaft and *having'thereon an internal key engaging one ofsaidfiatsbetween said longi: tudinal centerline of said. onetflat and one of saidlongitudinal edges of 'said 'onedlat upon relative rotation of said shaft and said member, said shaft engaging the interior of said member adjacent said longitudinal edges of the other of said "flats upon said relativej'rotation ofgsaid shaft and,

said member.

3. In combination: a shaft having two substantially di- 'ametrically opposite, longitudinally extending flats each having two longitudinal edges and a longitudinal centerline midway between its said longitudinal edges; and a member having an opening "(therein which receives said shaft and whichgis provided with a peripheral wall surrounding'saidyshaft, part of said peripheral wall of said opening being formed by an internalkey carriedby said member and engaging one of said flats between said longitudinal centerlineof said one flatand one of said longitudinal edges of said one flat upon relative rotation of said shaft andjsaid member, longitudinal portions of said 'shaft adjacent said longitudinal'edges of the other of said flats engaging :circumferentia'lly spaced longitudinal portions of said peripheral wall of said opening upon relative I rotation of 'said "shaft and-said: member, said longitudinal portions of said, peripheral wall'of said opening being spaced circumferentially from said key.

References Cited'in the file of this patent UNITED STATES PATENTS Blake Oct. 5, 1909 ,Habach Mai-.17, 1939 

